Asymmetric crack wake plasticity - a reason for roughness induced crack closure

Asymmetric arrangement of geometrically necessary dislocations in the wake of a crack tip induces a mismatch of fracture surfaces. It can explain the occurrence of the roughness induced crack closure far behind the fatigue crack tip. The asymmetric arrangement of geometrically necessary dislocations is verified by local crystal orientation measurements on fatigue crack in the near threshold regime in Cu and Fe. (C) 2004 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.